Appearing on CNN Wednesday afternoon following the scrapped infrastructure meeting between Trump and Democratic lawmakers, Sanders began by saying it was "outrageous" for the president to "storm out of the meeting."

"We have a president who is so sensitive, who attacks people, who humiliates people every single day," Sanders told CNN's Jake Tapper. "And if he can't take a little bit of criticism, he should think twice about being president of the United States."

When asked if he agreed with House Speaker Nancy Pelosi, D-Calif, about her claim that Trump "engaged in a cover-up," Sanders struggled to answer with certainty, telling Tapper it's "obviously very hard to get into the president’s mind" since he is a "pathological liar."

“I think if he continues to not understand the Constitution of the United States, the separation of powers, the fact that the Congress has every right to subpoena and it is the job of the administration to attend the hearings that the Congress is calling, if he doesn’t understand that, it may well be time for an impeachment inquiry to begin, where the Judiciary Committee begins to determine whether or not there are grounds for impeachment,” Sanders said.

A growing number of 2020 candidates have also expressed their support for impeachment, including Sen. Elizabeth Warren, D-Mass, Sen. Kamala Harris, D-Calif, and former congressman Beto O'Rourke.